From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from youngberry.canonical.com ([91.189.89.112]:58976 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750719AbcDKKCd (ORCPT ); Mon, 11 Apr 2016 06:02:33 -0400 Date: Mon, 11 Apr 2016 11:02:29 +0100 From: Luis Henriques To: Chas Williams <3chas3@gmail.com> Cc: stable@vger.kernel.org, Vitaly Kuznetsov , "K. Y. Srinivasan" , Greg Kroah-Hartman Subject: Re: [PATCH 3.14] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors Message-ID: <20160411100229.GE3379@ares> References: <1459175441-23154-1-git-send-email-3chas3@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1459175441-23154-1-git-send-email-3chas3@gmail.com> Sender: stable-owner@vger.kernel.org List-ID: On Mon, Mar 28, 2016 at 10:30:41AM -0400, Chas Williams wrote: > From: Vitaly Kuznetsov > > commit e513229b4c386e6c9f66298c13fde92f73e6e1ac upstream. > > When an SMP Hyper-V guest is running on top of 2012R2 Server and secondary > cpus are sent offline (with echo 0 > /sys/devices/system/cpu/cpu$cpu/online) > the system freeze is observed. This happens due to the fact that on newer > hypervisors (Win8, WS2012R2, ...) vmbus channel handlers are distributed > across all cpus (see init_vp_index() function in drivers/hv/channel_mgmt.c) > and on cpu offlining nobody reassigns them to CPU0. Prevent cpu offlining > when vmbus is loaded until the issue is fixed host-side. > > This patch also disables hibernation but it is OK as it is also broken (MCE > error is hit on resume). Suspend still works. > > Tested with WS2008R2 and WS2012R2. > > Signed-off-by: Vitaly Kuznetsov > Signed-off-by: K. Y. Srinivasan > Signed-off-by: Greg Kroah-Hartman > [ 3chas3@gmail.com: rebase to 3.14-stable ] Thanks, I'm also queuing this for the 3.16 kernel as well. Cheers, -- Lu�s > Signed-off-by: Chas Williams <3chas3@gmail.com> > --- > drivers/hv/vmbus_drv.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 077bb1b..e3b7341 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -31,6 +31,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -689,6 +690,39 @@ static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc) > desc->action->handler(irq, desc->action->dev_id); > } > > +#ifdef CONFIG_HOTPLUG_CPU > +static int hyperv_cpu_disable(void) > +{ > + return -ENOSYS; > +} > + > +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) > +{ > + static void *previous_cpu_disable; > + > + /* > + * Offlining a CPU when running on newer hypervisors (WS2012R2, Win8, > + * ...) is not supported at this moment as channel interrupts are > + * distributed across all of them. > + */ > + > + if ((vmbus_proto_version == VERSION_WS2008) || > + (vmbus_proto_version == VERSION_WIN7)) > + return; > + > + if (vmbus_loaded) { > + previous_cpu_disable = smp_ops.cpu_disable; > + smp_ops.cpu_disable = hyperv_cpu_disable; > + pr_notice("CPU offlining is not supported by hypervisor\n"); > + } else if (previous_cpu_disable) > + smp_ops.cpu_disable = previous_cpu_disable; > +} > +#else > +static void hv_cpu_hotplug_quirk(bool vmbus_loaded) > +{ > +} > +#endif > + > /* > * vmbus_bus_init -Main vmbus driver initialization routine. > * > @@ -747,6 +781,7 @@ static int vmbus_bus_init(int irq) > if (ret) > goto err_alloc; > > + hv_cpu_hotplug_quirk(true); > vmbus_request_offers(); > > return 0; > @@ -984,6 +1019,7 @@ static void __exit vmbus_exit(void) > bus_unregister(&hv_bus); > hv_cleanup(); > acpi_bus_unregister_driver(&vmbus_acpi_driver); > + hv_cpu_hotplug_quirk(false); > } > > > -- > 2.5.0 > > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html